Optimal Leveraging of a Gifford-McMahon Cryocooler’s Regenerative Cooling Power for SNSPD Applications

Abstract

Superconducting nanowire single photon detectors (SNSPDs) offer unparalleled efficiency, minimal dark count rates, and picosecond jitter, making them ideal for single photon detector applications across the visible to mid-IR spectrum. A common cryogenic system used to reach these detectors’ optimal operating temperatures (>1 K) consists of Sumitomo’s compact RDK101 Gifford McMahon Cryocooler (GMC) running on an Zephyr air cooled compressor, coupled with a helium four (4He) adsorption stage. In this work, our aim is to provide measurements of the RDK101 GMC second stage regenerator tube cooling power at several locations along its length. We then characterise the performance of the adsorption cooler with heat loads applied to the regenerator tube. Our measurements demonstrate that heat loads of 1.2 W can be intercepted at the tube’s section near the GMC’s first cooling stage, with a negligible effect on the performance of the adsorption cooler. The thermal conductivity of yellow brass coaxial was characterised from 4 K to 40 K. Here we show that the heat load from 64 coaxial cable can be optimally intercepted with the defined regenerator cooling power. These results indicate that a 1024-pixel SNSPD array using a 32x32 row column multiplexing architecture could be successfully implemented in this cryogenic platform.